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NDL (Network Definition Language) was a compiler on Burroughs Large and Medium Systems computers used to create a network definition file for a data communications controller (DCC) and object code for a data communications processor (DCP) that interfaced between a message control program (written in DCALGOL) such as (RJE), (MCSII) or (CANDE) and the computer's line adaptors and terminal network.^[1][2]

Burroughs Network Definition Language allowed many parameters of the mainframe communications adapter, modems (where used), protocol and attached terminal to be defined. However it treated the low-level operation of the multi-drop protocol, including the modulus of sequence numbers and the algorithm used for CRCs etc. as primitives.

• NDL Language Reference Manual